The present invention relates to bag closures in general and to closures for "poly" bags in particular.
Many industries utilize polyethylene or other thin plastic bags to package commodities, one of the most common industries being the food industry. Many foodstuffs are packaged in this way, for example, bread and milk. Most consumers are well-acquainted with the "pony-tail" bread bag and most are aquainted with the overbag containing a number of 1-quart pouches of milk. In both instances, it is necessary to open and close the covering bag a number of times before the contents thereof are exhausted. This means that a bag closure which can be positioned by automatic machinery and which can be removed and reused by the consumer must be provided. Many such closures have been proposed and many are in commercial use. For example, there is a closure made from a sheet of plastics material and having a C-shaped opening at one end. The bunched bag sides are positioned in the opening and the edge thereof retains the bag sides therein. This closure has the disadvantage that during handling portions of the bag sides can slip through the open area of the closure allowing air to enter the bag and perhaps allowing bag contents to eventually leave the bag. Also, the size of the opening in the closure must be tailored to the size of the bag to be closed. If the opening is too big or too small an improper closure will result.
An improved closure is found in U.S. Pat. No. 3,673,640 issued on July 4, 1972 to Dwight C. Brown. That closure includes a bowed strap and a clamping bar struck from the interior thereof and hinged at one end to the strap. A locking hook is provided at the other end of the bar for engagement with an edge of the strap in the opening left by the bar. The bunched bag sides are locked between the bar and the strap when the hook has engaged the strap. This closure eliminates any problems of inadvertent bag opening and also permits greater latitude in the size of the bag that can be closed thereby. However the tooling to produce the closure is expensive as the closure is complex in configuration, requiring a number of steps to bow the strap, form the clamping bar and form the hook thereon. The configuration also fails to provide areas for imprinting, an important feature with respect to mounting consumer interest in price, quality, weight and dates of latest use.